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From: Kees Cook <keescook@chromium.org>
To: Changbin Du <changbin.du@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/slub: do not place freelist pointer to middle of object if redzone is on
Date: Sat, 25 Apr 2020 15:48:31 -0700	[thread overview]
Message-ID: <202004251547.0F8E6856B@keescook> (raw)
In-Reply-To: <20200425091338.24283-1-changbin.du@gmail.com>

On Sat, Apr 25, 2020 at 05:13:38PM +0800, Changbin Du wrote:
> The recent kernel fails to boot when slub redzone is turned on. This is
> caused by commit 3202fa62fb ("slub: relocate freelist pointer to middle of
> object") which relocates freelist pointer to middle of object. In this
> case, get_track() gets a wrong address and then the redzone is overwritten.

Hi! A fix for this is already in -next:

https://www.ozlabs.org/~akpm/mmotm/broken-out/slub-avoid-redzone-when-choosing-freepointer-location.patch

the above doesn't disable the mitigation when using redzones, so I
prefer that to this suggested solution.

-- 
Kees Cook


  reply	other threads:[~2020-04-25 22:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-25  9:13 [PATCH] mm/slub: do not place freelist pointer to middle of object if redzone is on Changbin Du
2020-04-25 22:48 ` Kees Cook [this message]
2020-04-26  0:07   ` Changbin Du
2020-04-25 20:24 Markus Elfring
2020-04-25 23:51 ` Changbin Du

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